I would only use the router with tomato for this one device, so this router would only get an internal IP address. Can I then specify in tomato somewhere that it should use a proxy with an internet IP address or a Gateway. I have root access to the (Linux) server with the proxy on (at the other side of the world).

Objective: be able to use the proxy's IP address and hostname for the device here so it appears that the device is hosted there.